CN102811916B - For thermoformed container assembly and the manufacturing method for container of food - Google Patents

Abstract

A kind of container for the formation of holding food also comprises the assembly of thermoforming sleeve and base portion.Sleeve comprises frustoconical side walls, upper lip and lower lip.Sidewall limits isolated handle part in inside face, outside face and multiple circumference, and handle part comprises the recessed and corresponding inner surface protrusion of outside face.Upper lip is radially inwardly given prominence to from the upper end of sleeve generally, and lower lip generally from lower end radially outwardly.Base portion and sleeve separate and are formed, and can be assembled in lower end to seal under shed.In some embodiments, each of multiple handle part is wedge shape.In other detailed description of the invention, base portion is thermoformed components, and is ultrasonically welded to lower lip.

Description

Thermoformed container assembly for food and method of making the container

technical field

This disclosure relates to plastic containers. More particularly, it relates to thermoformed containers for containing food products.

Background technique

One area where the use of plastic containers has been widely developed is in the food packaging industry. Thus, it is common for these plastic food containers to be used as terminal display packaging for food products sold to consumers. Those containers for dairy products such as cottage cheese, sour cream, etc. are typical of these containers, wherein the integral body of the container is provided with a downwardly tapering from a larger diameter top opening to an integral, transverse The side walls of the bottom wall, and the top opening are closed by separate, plug-fit covers. Typically, the lid has a depending peripheral skirt that locks to the upper rim of the tapered wall of the container body.

Somewhat related current plastic food container designs for flavored yogurt provide an inverted tapered sidewall body or sleeve forming a smaller diameter top opening and a larger diameter bottom opening. A separate bottom closure seals the bottom opening so that yogurt (or other food product) can be received and contained within the main body. The bottom closure includes a base plate, and a dependent skirt wall attached (eg, spin welded) to the interior surface of the body to permanently attach the pieces to each other. Thus, unlike the aforementioned top closure lids that are designed to be opened (i.e., removed from the larger diameter opening of the container), the bottom closure for this particular yogurt container does not have a rim that otherwise locks to the side wall Locking skirt that goes on and can be opened to access the food contained within. Instead, the bottom closure is secured to the body and after filling with yoghurt, the top opening is sealed closed by a soft foil adhered to the lip of the body. To access the yogurt, peel the seal from the top opening.

In some instances, regardless of final shape, plastic food containers have their parts formed by a thermoforming process. In thermoforming, a thin sheet of plastic is formed into a desired shape by heating and forcing the sheet against a mold to produce a container part with a uniform, very thin thickness that can result in a very soft wall. Section thickness of the part. For example, the yogurt container described above is initially manufactured by thermoforming the body and bottom closure, and then spin welding these parts for permanent attachment. In an effort to address the perceived issues associated with these previous thermoformed and spin welded yogurt containers, an injection molded construction was designed and described, such as in US Patent No. 6,213,301. Generally speaking, the '301 patent describes a two-piece injection molded plastic container in which an injection molded frustoconical body portion is ultrasonically welded to an injection molded lower body portion (serving as a bottom closure). The ribs are formed on the exterior of the body portion and facilitate the stacking of multiple body portions compatible with each other, spaced apart, such as during transport and/or in high speed automated feeding equipment. Similarly, internal ribs are formed along the lower portion and facilitate their desirably spaced stacking.

While the injection molded plastic containers of the '301 patent are highly feasible, opportunities for improvement still exist. With injection molding, for example, relatively large quantities of plastic resin are required in order to obtain the desired rigidity of the container. Additionally, gate marks inherent to injection molding can get in the way of multiple production steps, such as when trying to evenly adhere a foil seal to a lip.

In view of the above, there exists a need for improved food containers.

Contents of the invention

Some aspects in accordance with the principles of the present disclosure relate to a container assembly for forming a container for containing food products. The assembly includes a thermoformed sleeve and a base. The sleeve has upper and lower openings and includes frustoconical sidewalls, and upper and lower lips. The sidewall defines a diameter that increases from an upper end to a lower end. Additionally, the sidewall defines an inner surface, an outer surface, a plurality of circumferentially spaced indentations, and a plurality of protrusions. The recess is formed on an outer surface adjacent to the upper end. The protrusions are formed on the inner surface, while each of the protrusions corresponds to each of the recesses. The upper lip generally projects radially inwardly from the upper end to define the upper opening. The lower lip generally projects radially outward from the lower end. The base is formed separately from the sleeve and is assembleable to the lower end to seal the lower opening. In some embodiments, each of the plurality of recesses is wedge-shaped, while the outer surface tapers inwardly toward the central axis of the sleeve from the front side to the rear side. In a related embodiment, said inner surface defines the same taper along each protrusion in the formation of a shoulder serving as an adjoining region of an upper lip for engaging an identical second sleeve internally stacked therein. In other specific embodiments, the base is a thermoformed component and is ultrasonically welded to the lower lip.

Other aspects in accordance with principles of the present disclosure relate to methods of making containers for containing food products. The method comprises thermoforming the sleeve and thermoforming the base as described above. The base includes an annular wall and a flange. The annular wall is inserted into the lower opening of the sleeve and the flange is positioned adjacent to the lower lip. Ultrasonic energy is applied to the lower lip such that the lower lip and the flange are welded to each other.

Description of drawings

FIG. 1 is an exploded perspective view of a container assembly in accordance with the principles of the present disclosure;

Figure 2 is a cross-sectional view of the sleeve portion of the assembly of Figure 1;

Figure 3 is an enlarged cross-sectional view of a portion of the sleeve of Figure 2, showing its grip and upper lip portion;

4A is an enlarged cross-sectional view showing a portion of two sleeves in accordance with principles of the present disclosure stacked one on top of the other in a compact, vertical arrangement;

4B is an enlarged cross-sectional view of another portion of the stacked sleeve arrangement of FIG. 4A;

Figure 4C is an enlarged cross-sectional view of another portion of the stacked sleeve arrangement of Figure 4A;

Figure 5 is an enlarged cross-sectional view of a portion of the sleeve of Figure 2, showing its lower lip;

Figure 6 is a cross-sectional view of the base portion of the assembly of Figure 1;

Figure 7 is an enlarged cross-sectional view of a portion of the base of Figure 6;

8 is an enlarged cross-sectional view of a portion of two bases in accordance with principles of the present disclosure stacked one on top of the other in a compact, vertical arrangement;

Figure 9 is an enlarged cross-sectional view of a portion of the base of Figure 6, showing its lower flange; and

Figure 10 is a side plan view of the container assembly of Figure 1 in a final constructed state.

Detailed ways

One embodiment of a container assembly 20 for forming a food container is shown in FIG. 1 and includes a sleeve 22 and a base 24 . In general, the base 24 is configured to be attached to the bottom of the sleeve 22 to form an open top container for filling food products. In some configurations, the container is used for yogurt and the exemplary dimensions described herein for the sleeve 22 and base 24 are for a container filled with 6 ounces (170 g) of flavored yogurt; however, it will be understood that the container The size and corresponding dimensions of the assembly components 22, 24 may vary from those described herein and still fall within the scope of the present disclosure. Similarly, other food types or forms may be accommodated by the container. After filling, the open top can then be closed by a thin sealing (eg, foil) member 26 that is removably adhered to the top of the sleeve 22 for sealing the food product inside the container.

Sleeve 22 includes or defines a sidewall 30 , an upper lip 32 , and a lower lip 34 . The side wall 30 forms the inner container region 36 and has a generally frusto-conical shape expanding in diameter from a smaller diameter upper end 40 to a larger diameter lower end 42 . With additional reference to FIG. 2 , the sidewall 30 defines an inner surface 44 and an outer surface 46 . With these conventions in mind, a plurality of grips 48 are formed on the sidewall 30 proximate to the upper end 40 (e.g., in some embodiments, the grips 48 represent 0.01-0.10 inches (0.254-2.54 inches) from the upper end 40 mm) starting at some deviation from an otherwise uniform frustoconical shape). Grips 48 may be identical in size, shape, and vertical distance from upper end 40 and circumferentially spaced (eg, equidistantly spaced) from one another. In some configurations, four grips 48 are provided, but other numbers, such as six, eight, etc., are also acceptable.

Each grip 48 includes or defines a recess 50 along the outer surface 46 and a protrusion 52 along the inner surface 44 . In some embodiments, the sidewall 30 has a uniform thickness (at least along the region of the grip 48 ), such that the dimensional properties of the recess 50 and corresponding protrusion 52 may be the same or substantially the same. For example, a handle 48 is shown in more detail in FIG. 3 . With respect to the vertical orientation of the sidewall 30 , the handle 48 may be described as having a front side 54 and a rear side 56 . A front side 54 is defined proximate to upper end 40 (and upper lip 32 ), while a rear side 56 is defined opposite front side 54 . With these conventions in mind, recess 50 is characterized by outer surface 46 tapering radially inwardly from front side 54 to rear side 56 (i.e. 30 frusto-conical top-to-bottom enlargement (or inverted cone deviation). For example, with respect to the vertical centerline C of the sleeve 22, the outer surface 46 defines a taper angle θ in the range of 1°-20°, optionally 10°, from the front side 54 to the rear side 56. . The longitudinal (or vertical) height (ie, the axial distance between the front side 54 and the rear side 56 ) of the grip 48 may be about 0.20-0.42 inches (5.08-10.67 mm), optionally 0.313 inches ( 7.95mm). With this configuration, the recess 50 provides an area for convenient insertion of a user's fingertip in order to remove the foil seal 26 ( FIG. 1 ) otherwise applied to the upper lip 32 as described below.

Protrusion 52 is characterized by inner surface 44 tapering radially inwardly toward vertical centerline C in the range from front side 54 to rear side 56 (ie, from the side that occurs at the region other than grip 48 The frusto-conical top-to-bottom enlargement of wall 30 deviates). With the embodiment in which sidewall 30 has a uniform thickness at least along grip 48 , inner surface 44 defines the same taper angle θ along protrusion 52 ranging from front side 54 to rear side 56 . In other embodiments, the thickness of sidewall 30 may vary. Regardless, a shoulder 60 is defined by the inner surface 44 at the rear side 56 . Shoulder 60 is adapted to facilitate desired stacking. As best shown in FIG. 2 , the shoulder 60 may have a 0.5-in. (12.7mm) circumferential width W, and has a relatively large surface area compared to conventional vertically oriented stacked ribs. In particular, and as shown in FIG. 2 , the shoulders 60 of each projection 52 are circumferentially flush and join to establish a stacking plane P longitudinally spaced apart from the upper ends 40 and adapted to contact nested sockets. 22 in a separate sleeve. With embodiments in which sidewall 30 has a relatively uniform thickness at least along grip 48, corresponding recess 50 has a corresponding circumferential width (e.g., about 0.4-0.6 inches (10.16- 15.24mm), optionally 0.5 inches (12.7mm)). The circumferential width optionally tapers from the rear side 56 to the front side 54 in some embodiments.

For example, FIG. 4A shows a stacked assembly of a first (or inner) sleeve 22a within a second (or outer) sleeve 22b. As shown, the upper lip 32a of the first sleeve 22a contacts or abuts the shoulder 60b of the second sleeve 22b. A similar abutment relationship is established between the upper lip 32a of the first sleeve 22a relative to the shoulder 60b formed by the remaining grip 48b associated with the second sleeve 22b along the stacking plane P. With this arrangement, shoulder 60b then ensures sufficient stacking spacing between upper lips 32a, 32b (eg, about 0.3 inches (8.2 mm) in some embodiments). This spacing may also be referred to as the stack height of the sleeves 22a, 22b. Conventionally, however, stack height is with respect to the longitudinal distance between external features. As shown in Figure 4B, then, the engagement between the upper lip 32a (Figure 4A) of the first sleeve 22a and the shoulder 60b (Figure 4A) of the second sleeve 22b defines the stack height between the lower lips 34a, 34b H ₁ , height H ₁ may be in the range of 0.2-0.6 inches (5.1-15.2 mm), alternatively 0.305-0.505 inches (7.751-12.83 mm), optionally 0.381 inches (9.677 mm). Also, FIG. 4C illustrates maintaining a small air gap G1 between the stacked sleeves 22a, 22b, which in some embodiments may be approximately approximately 0.004 inches (0.105 mm). In this way, the sleeves 22a, 22b can be stacked in a compact, vertical arrangement for significant savings in shipping costs because a large number of sleeves 22 can be stacked in a given space.

Returning to FIG. 3, in addition to the handle 48, in some configurations the sidewall 30 is linear or uniform from the upper end 40 to the lower end 42 (FIG. 0.508 mm), optionally 0.012 inches (0.305 mm) of uniform thickness. Alternatively, other features and/or thickness variations may be provided.

The upper lip 32 generally projects radially inwardly from the upper end 40 of the side wall 30 , terminating at an annular rim 70 that otherwise defines an upper opening 72 to the interior region 36 . In some constructions, at least a portion of the upper lip 32, optionally overall, has a wall thickness greater than the thickness of the sidewall 30; for example, the upper lip 32 may have a wall thickness in the range of 0.016-0.026 inches (0.406-0.660 mm), Optionally 0.021 inches (0.53mm) thick. Regardless, upper lip 32 includes or defines a first segment 80 extending from sidewall 30 , and a second segment 82 extending from first segment 80 to edge 70 . An annular peak 84 is formed at the intersection or transition of the segments 80 , 82 . The annular peak 84 defines the uppermost plane U of the sleeve 22 and serves as an attachment point or surface for the seal 26 ( FIG. 1 ). As shown, the annular peak 84 is radially offset or away from the edge 70 of the upper lip 32 and is highly smooth and continuous (eg, does not form a raised gate mark) to provide a clean surface for bonding the seal 26. surface.

The first segment 80 extends upwardly (with respect to the vertical direction in FIG. 3 ) and radially inwardly from the upper end 40 of the side wall 30 . For example, in some configurations, the extension of the first segment 80 defines an angle Δ with respect to the upper plane U in the range of 19°-29°, optionally 24°. The second segment 82 is downward from the first segment 80 (relative to the vertical direction of FIG. 3 ) and radially inward to the terminal edge 70 . For example, with respect to the outer surface 86 of the upper lip 32 (and the vertical direction in FIG. 3 ), the distal edge 70 is lower than the annular peak 84 by a vertical distance in the range of 0.008-0.018 inches (0.203-0.457 mm). range, optionally 0.013 inches (0.33mm). Alternatively, other dimensions are acceptable. In some embodiments, however, the terminal edge 70 is lower than the annular peak 84 such that the terminal edge 70 does not prevent the seal 26 ( FIG. 1 ) from attaching to the peak 84 or otherwise visibly contacting the seal 26 .

As shown in FIG. 5 , the lower lip 34 extends radially outward from the lower end 42 . With this configuration, a lower opening 89 to the interior region 36 is defined at the lower end 42 . Alternatively, additional radially inward structures may be further included. Regardless, the lower lip 34 defines an upper surface 90 and an opposing lower surface 92 . Upper surface 90 "faces" upper end 40 of sidewall 30 ( FIG. 2 ), while lower surface 92 is defined opposite upper surface 90 (ie, upper surface 90 is above lower surface 92 relative to vertical in FIG. 5 ). In some configurations, lower lip 34 has a thickness (ie, the dimension between upper surface 90 and lower surface 92 ) of about 0.046-0.056 inches (1.168-1.422 mm), optionally 0.051 inches (1.30 mm). . In addition, an annular protrusion 94 is optionally provided to protrude downward from the lower surface 92 . The annular projection 94 has opposing sides 96 , 98 (in transverse cross-section) forming an angle α extending from the lower surface 92 . In some configurations, the included angle α is in the range of 50°-70°, optionally 60°. Additionally, annular projection 94 may have a height relative to lower surface 92 of approximately 0.010-0.020 inches (0.254-0.508 mm), optionally 0.015 inches (0.38 mm). However, if provided, the annular projection 94 may have a domed triangular cross-sectional shape and serve as an energy director for use in connection with the ultrasonic welding operation between the sleeve 22 and the base 24 ( FIG. 1 ) as described below ( director). Alternatively, the annular protrusion/energy director 94 may be provided by the base 24 (FIG. 1), while the lower surface 92 is optionally textured in these alternative embodiments.

Returning to FIG. 1 , with additional reference to FIG. 6 , the base 24 includes a skirt wall 100 , a platform 102 , and a flange 104 . Generally speaking, the skirt wall 100 is sized for insertion into the lower opening 89 ( FIG. 2 ) of the sleeve 22 , while the platform 102 is used to close the lower opening 89 . Flange 104 provides a surface for ultrasonic welding of components 22 , 24 .

The skirt wall 100 has a frusto-conical shape expanding in diameter from a smaller diameter top end 110 to a larger diameter bottom end 112 . Additionally, the skirt wall 100 defines an interior surface 114 and an exterior surface 116 . With these specified considerations, the skirt wall 100 forms at least one grip 118 proximate to the top end 110 (eg, the grip 118 appears to deviate from the otherwise uniform frustoconical, inverted cone shape of the skirt wall 100 ). In one configuration of FIGS. 1 and 6 , a single grip 118 is formed; however in other embodiments, the skirt wall 100 may define a plurality of grips 118 varying in size, shape, and distance from the top end. 110 are identical in vertical distance and are circumferentially spaced (eg, equidistantly spaced) from each other. With these alternative configurations, the skirt wall 100 may optionally include four, six, etc. grips 118 .

Grip 118 includes or defines a ridge 120 along interior surface 114 . In some embodiments where the skirt wall 100 has a uniform thickness (e.g., about 0.005-0.020 inches (0.127-0.508 mm), optionally 0.012 inches (.0305 mm)) along the region of the handle 118, along the outer surface 116 forms a corresponding recess 122 . With respect to the vertical orientation of the base 24 in the cross-sectional view of FIG. Project radially inwardly from 130 to rear side 132 . In some embodiments, the inner surface 114 is formed along the bulge 120 at a taper angle δ in the range of 7°-17°, optionally 12°, relative to the vertical centerline B of the skirt wall 100 . The outer surface 116 can have similar dimensional properties in the optional, corresponding placement of the recesses 122 . Regardless, a rim 134 is formed by the inner surface 114 at the rear side 132 and defines a stacking plane S. As shown in FIG. For reference purposes, an alternative embodiment incorporating a plurality of circumferentially spaced grips 118 each forming a rim segment with the rim segments joining to define a stacking plane S is employed. Then, as shown in FIG. 8 , the platform 102 a of the first base 24 a will abut the rim 134 b of the second base 24 b along the stacking plane S when the first base 24 a is nested within the second base 24 b. In some configurations, the base 24 is sized to provide a range of 0.05-0.5 inches (1.27-12.7 mm), alternatively 0.066-0.266 inches (1.67-6.76 mm), optionally 0.166 inches (4.22 mm) stack height H2, but other stack heights are also acceptable.

Returning to FIGS. 1 and 7 , the platform 102 extends beyond the top end 110 of the skirt wall 100 and may include an outer ring segment 140 and a dome segment 142 . Ring segment 140 may be relatively planar (horizontal with respect to the orientation of FIGS. 1 and 7 ), having a radial width of approximately 0.26-0.29 inches (6.60-7.37 mm), optionally 0.2735 inches (6.950 mm) . The dome segment 142 may include a rim portion 144 and a center portion 146 . The rim portion 144 generally extends radially inwardly from the ring segment 140 and may form an extension angle β in the range of 20°-40°, optionally 30°. Central portion 146 extends beyond rim portion 144 and is planar (eg, horizontal) in some configurations. Alternatively, platform 102 may assume various other shapes or forms.

Referring specifically to FIG. 9 , the flange 104 extends radially outward from the bottom end 112 of the skirt wall 100 and defines a top surface 150 and a bottom surface 152 . In some configurations, the bottom surface 152 is planar and establishes a face for maintaining the base 24 on a flat surface (eg, a tabletop) in a vertical direction. The top surface 150 may include or form a raised shelf 154 having a front face 156 . Front face 156 is relatively planar, but provided with surface texture (eg, a textured or rough pattern embedded to a depth of about 0.0045 inches (0.1143 mm) in some embodiments). Alternatively, raised shelf 154 may be eliminated and the entirety of top surface 150 provided with the above-described texture. Still further, the boss 154 may be formed as an ultrasonic welding energy director. Regardless, and as described in more detail below, flange 104 provides a surface for ultrasonic welding to sleeve 22 ( FIG. 1 ), and in some embodiments has a thickness greater than that of skirt wall 100 ( For example, the thickness of the flange 104 between the surfaces 150, 152 may be approximately twice the nominal thickness of the skirt wall 100).

Returning to FIG. 1 , in some embodiments at least the sleeve 22 , and in other embodiments both the sleeve 22 and the base 22 are thermoformed components. For example, the sleeve 22 may be a monolithically formed homogeneous body thermoformed from a polypropylene-based plastic sheet. The base 24 may similarly be a monolithically formed homogeneous body thermoformed from a polypropylene-based plastic sheet. Stamping or down holder techniques may be used to create elevated thickness along certain portions of one or both components (eg, protrusions/energy directors 94 (FIG. 5)). The thermoformed two-piece container construction of the present disclosure requires less material to achieve similar wall strength compared to existing injection molded two-piece frusto-conical container designs for holding 6 ounces (170 g) of yogurt . This translates into substantial cost savings. Additionally, due to the use of thermoforming techniques, the sleeve 22 and base 24 components are produced without gate marks or other defects that might otherwise adversely affect performance.

Referring to FIGS. 1 and 10 , construction of the container assembly 20 includes positioning the base 24 within the sleeve 24 . In particular, the platform 102 and skirt wall 100 of the base 24 are inserted within the lower opening 89 of the sleeve 22 ( FIG. 2 ), while the lower lip 34 of the sleeve 22 abuts the flange 104 of the base 24 . The parts 22, 24 are then brought together into the ultrasonic fixture and ultrasonically welded to each other. For example, with an embodiment where the lower lip 34 includes an annular protrusion/energy director 94, an ultrasonic horn is placed in contact with the lower lip 34 and the applied ultrasonic energy. In response to the high frequency vibration, the annular protrusion/energy director 94 (FIG. 5) melts and bonds to the shelf 154 (FIG. 9) of the flange 104 to achieve a permanent weld, while the asperities 156 (FIG. 9) increase the adjacent surface area in order to increase the frictional heat generated between vibrating surfaces. Alternatively, an energy director may be provided by flange 104 . After welding, the base 24 closes the lower opening 89 of the sleeve 22 . Foodstuffs (eg, flavored yogurt) are then dispensed within interior region 36 before seal 26 is applied to upper lip 32 and, in particular, by bonding to annular peak 84 .

The food container assembly 20 of the present disclosure provides a significant improvement over previous designs. By using thermoforming techniques with desired materials such as polypropylene based materials, overall container strength is maintained and substantial cost savings are also realized. Additionally, the recess formed by the sleeve provides a convenient area for a user's fingers to rest when attempting to remove the foil member. Finally, the desired stacking arrangement of the sleeve and the base relative to each other is obtained.

Although the present disclosure has been described with reference to preferred specific embodiments, workers will recognize that changes may be made in form and detail without departing from the spirit and scope of the disclosure.

Claims (21)

1. Assemblies for forming containers for containing food, said assemblies comprising: A thermoformed sleeve having an upper opening and a lower opening, said sleeve comprising: A frusto-conical side wall having a diameter that expands from an upper end to a lower end, the side wall defining: The inner surface, The outer surface, a plurality of circumferentially spaced grips adjacent said upper end and each said grip includes a recess along said outer surface and a corresponding protrusion along said inner surface, an upper lip projecting generally radially inwardly from said upper end to define said upper opening, a lower lip projecting generally radially outward from said lower end; and A base formed separately from the sleeve and assembleable to the lower lip to seal the lower opening. 2. The assembly of claim 1 , wherein each of said protrusions is defined by a shoulder opposite said upper end, said shoulders being circumferentially flush to collectively define said upper lip for engaging identical inner stacked sleeves stack plane. 3. The assembly of claim 1, wherein each said recess is wedge-shaped. 4. The assembly of claim 3, wherein said wedge shape comprises a front side proximate to said upper end and a rear side opposite said upper end, and further wherein said outer surface extends from said front side to said rear side The range tapers inwardly towards the vertical centerline of the sleeve. 5. The assembly of claim 4, wherein each of said plurality of grips includes said inner surface defining the same taper angle as defined by said outer surface along said corresponding recess . 6. The assembly of claim 1, wherein said plurality of grips includes only four of said recesses. 7. The assembly of claim 1, wherein said upper lip has a greater thickness than said sidewall. 8. The assembly of claim 1 , wherein said upper lip comprises a first section extending from said upper end and a second section extending from said first section toward a terminal edge, and further wherein said sleeve Vertically, the first segment extends upwardly and radially inwardly from the sidewall, and the second segment extends downwardly and radially inwardly from the first segment. 9. The assembly of claim 8, wherein an annular peak of said upper lip is defined at the intersection of said first and second segments, said annular peak being defined for receiving a The highest plane of the sleeve of the flexible seal. 10. The assembly of claim 9, wherein said annular peak is radially spaced from said terminal edge. 11. The assembly of claim 1 , wherein the lower lip has a greater thickness than the sidewall. 12. The assembly of claim 1, wherein said lower lip defines an upper surface facing said upper opening and a lower surface opposite said upper surface, and further wherein said lower lip forms a Circumferential protrusion of a surface. 13. The assembly of claim 12, wherein said circumferential projection protrudes below said lower end of said side wall with respect to a vertical direction of said sleeve. 14. An assembly according to claim 12, wherein in final assembly the protrusion is welded to the base. 15. The assembly of claim 1, wherein the base is a thermoform. 16. The assembly of claim 1, wherein said base comprises: a frustoconical skirt wall having a diameter increasing from the top end to the bottom end, the skirt wall defining an inner surface and an outer surface; a platform extending beyond said tip; and a flange extending generally radially outward from the bottom end; wherein said skirt wall is sized to nest within said lower opening of said sleeve with said lower lip adjacent said flange. 17. The assembly of claim 16, wherein said skirt wall forms a ridge along said interior surface proximate said top end. 18. The assembly of claim 17, wherein the skirt wall has a uniform thickness. 19. The assembly of claim 16, wherein said flange has a greater thickness than said skirt wall. 20. The assembly according to claim 16 , wherein said flange defines a horizontal bottom surface and a top surface opposite said bottom surface with respect to a vertical direction of said base, said flange also forming a A longitudinally protruding annular frame, and further wherein one face of said frame is roughened. 21. A method of making a container for containing food, the method comprising: Thermoforming said base and said sleeve of claim 1; Assembling the base within the lower opening of the sleeve; and The sleeve and the base are ultrasonically welded.